what are peoples thoughts on this...? The main difference obviously is that the first one is a all-in-one computer and the other is a notebook the other would be that one is slightly cheaper being a couple of hundred dollars then the other.

No experience with the All In Ones from Dell. When they do new stuff like that it makes me nervous. I like to stick to their tried and true business lines. However, it looks pretty awesome and the specs are not bad.

The only thing I would recommend for which ever you end up going with is to bump that 4GB to 8GB of RAM. If you want to pound a bunch of VMs at once, that will come in handy.